Neurovascular Non Contrast-Enhanced MR Angiography at 3T

MR angiography (MRA) has become essential in the treatment of neurovascular diseases, including ischemic stroke - the first cause of disability in occidental countries, vascular malformations such as aneurysms, arteriovenous fistulas and malformations, whose treatments are improving year after year. MRA is an alternative to digital substracted angiography (DSA), circumventing th use of endovascular catheterism, irradiation and injection of iodinated contrast agent. Contrast-Enhanced MRA (CE-MRA) with gadolinium injection is currently the reference standard for vascular MR exploration but still presents many limitations inherent to the injection of contrast medium. Hence, the synchronization of the acquisition with bolus contrast injection limits the improvement of spatial and temporal resolutions and requires an accurate synchronization of the acquisition with the arrival of the bolus. Moreover, the acquisition can be repeated as required as it does not require any contrast injection. Besides, the increase in nephrogenic systematic fibrosis clinical cases, which would be secondary to gadolinium chelates injection, in patients with chronic renal insufficiency has restricted the use of CE-MRA. More than 500 cases were described to date in the world. Its occurrence is currently estimated around 4 % for patients in terminal chronic renal insufficiency and its mortality around 30 %. According to the recommendations of AFSSAPS from August, 2007, two gadolinium contrast agent (Gadodiamide-OMNISCAN \*, General Electric HealthCare and Gadopentetate Dimeglumine-MAGNEVIST \*, Bayer HealthCare) are contraindicated if the glomerular filtration rate is lower than 30 ml/mn. Non-contrast enhanced MR angiography (NCE MRA) techniques have been proposed to provide complete and non-invasive investigation of the vasculature, thus offering patients with chronic renal insufficiency, as well as pregnant or nursing women a surrogate with no side effects. Moreover, the use of high fie